The invention relates to a magnetic head for use in vertical recording. The heading has a contact surface for a magnetic recording medium and a main magnetic pole of a thin film of soft magnetic material extending up to the contact surface and enclosed between first and second protective blocks together constituting the body of the magnetic head. The first protective block consists of a magnetic part and a non-magnetic part, the latter extending from the boundary surface of the two parts up to the contact surface. A channel provided at the boundary surface in the magnetic part causes a part constituting an auxiliary magnetic pole and adjoining the main magnetic pole to be separated from a part consituting the return path for the magnetic flux from the main pole, a winding embracing the main pole and the auxiliary pole being wound through the channel.
In the art of short wavelength magnetic recording it is known that vertical recording (that is to say, magnetisation in the direction of thickness of the magnetic tape)--is advantageous over recording in the longitudinal direction or the direction of movement of the magnetic tape. The reason is that the demagnetizing field within the magnetic layer increasing if the wavelength of the recording signal is decreased in the case of recording in the longitudinal direction, whereas this field decreases in the case of vertical recording.
Various constructions have been proposed for the magnetic head for vertical recording. If ideal magnetization is to be obtained in vertical recording, the main component of the magnetic field from the magnetic head should be as nearly as possible at right angles to the magnetic recording medium.
A previously proposed magnetic head for vertical recording is known DE-A-3421083 and comprises a main magnetic pole of a thin film of soft magnetic material enclosed between two protective blocks together constituting the body of the magnetic head. Each protective block consists of a magnetic and a non-magnetic part, the latter extending from the boundary surface of the two parts up to the contact surface between the main pole and the magnetic recording medium. Channels provided at the boundary surface in the magnetic parts of the protective blocks cause a part constituting an auxiliary magnetic pole and adjoining the main magnetic pole to be separated from parts constituting return paths for the magnetic flux from the main pole, a winding being wound around the magnetic auxiliary pole through the channels.
However, the previously proposed magnetic head has a number of drawbacks which are predominantly in the field of manufacture (technology). A serious drawback is that the head is built up of two pieces of material, each assembled from two parts using bonding techniques. Bonding between the non-magnetic upper blocks and the magnetic (ferrite) lower blocks sometimes poses problems, because great forces arise in the material and in the bonding surfaces during sawing and/or polishing of these assembles.
A further magnetic head for vertical recording is known from the aforementioned DE-A-3421083. In this magnetic head, which also comprises a main magnetic pole formed as a thin film and two protective blocks provided on either side thereof consisting of a magnetic and a non-magnetic part, channels provided in the magnetipart cause a separation in each protective block between a part located near the main magnetic pole and constituting an auxiliary magnetic pole, and a part constituting the return path for the magnetic flux from the main pole. An electromagnetic coil accommodated in the channels is provided around the assembly of main pole and auxiliary poles. The thin film is provided on a side face of an assembly of one magnetic and one non-magnetic part of the magnetic head.
After polishing such a face, a step can sometimes be formed in the surface. This is because polishing is not necessarily optimized for the two different materials. When the pole film, for example, NiFe is provided on this polished surface, this step may produce an interrupted pole. Moreover, this step is sometimes fatal to the bonding of the non-magnetic upper block and the magnetic lower block due to the forces exerted during bonding of the two core halves. Moreover, it is very disadvantageous to have to apply the pole film on an assembly of two different substrate materials due to the high quality of the film required (high .mu.hd r and B.sub.s).